1. Field of the Invention
Embodiments of the present invention is are related to a device and a method for ultrasound testing by means of local immersion technique of a stringer component section of a flat component.
2. Description of the Prior Art
A device as well as a method of the type mentioned above is described in patent US-A-2007/0044563. The device comprises a sensor holder which is designed to record one or several linear ultrasound sensors. The device lies on rollers on the flat component to be tested and is guided by an operator along the component section in the form of a band that is to be tested. The ultrasound sensors can be oriented in parallel or essentially in parallel to the surfaces to be tested, whereby the distance to the tested surface can be adjusted by means of an adjusting screw.
In the U.S. Pat. No. 7,464,596, a device for ultrasound testing of profiles, for example U-profiles, is described. The device comprises two sensor holders, of which at least one sensor holder is mounted in a mobile position along the guide rails, so that it can balance the oscillations of the profile to be tested.
An ultrasound sensor for testing of laminated structures, such as T or double-T profiles, is known from the U.S. Pat. No. 4,848,159. The device is designed in particular to detect errors in the radius area and in the surrounding areas of the laminated structure. The sensor comprises many sliders which are mounted in such a way as to guarantee a coordinated movement relative to the part to be tested. The holder comprises a great number of ultrasound transducers.
A method and a device for testing a component with a complex surface contour by means of ultrasound is described in patent DE-B-103 49 948. In this process a test head is moved by means of a multi-axial manipulator along a space curve at a distance in parallel to the surface of the tested component. Thereby the axle drives of a manipulator move synchronously along predetermined support points, whereby a trigger drive is moved in a synchronized manner, controlled with the axle drives and together with all axle drives in operation, according to a predetermined surface line reproducing the surface contour. The patent WO-A-03/065788 is related to a method and device for acoustic microscopy. The system comprises a controller and a “JIG,” which is mounted removably on the tested object. The “JIG” comprises an acoustic transducer connected to the controller, which controls the position of the acoustic transducer. The “JIG” is adjusted in a way that enables the controller to move the acoustic transducer over the object and to adjust its position during the scans in order to compensate the contours of the scanned section of the object.
Requirements for the ultrasound testing of airplane structural components are particularly high. There is not only the requirement that large-area outer walls be tested, but also, preferably, the so-called longitudinal stiffening girders (stringers), which are mounted in the inside area of the component, should be subjected to ultrasound testing. In some cases, the longitudinal stiffening girders can be tested separately before their integration into another structural element.
With the introduction of fiber composite materials in the aircraft construction, it is also possible to manufacture large-surface components directly with the help of integrated longitudinal stiffening girders (stringers), so that they have to be tested in their end state, i.e. as an integrated unit.
A special challenge for ultrasound testing is the transition area between the longitudinal stiffening girder (stringer) and the stiffened surface of the structural element. This transition is described as a “foot,” and poses a particular challenge for ultrasound testing, because this transition area is difficult to access in many cases.
In order to guarantee sufficient testing of this transition area as well as the stringer itself, a precise tracking control of the contour and gradient changes of the transition area and/or the profile of the stringer in the range of <1 mm by means of longitudinal extension of the stringer in the range of >5 m is necessary.
On the basis of the above requirements, until now ultrasound testing of this type of components was performed by means of manual testing because automatic testing, due to the difficult geometric and spatial characteristics, required very precise test head holders and guides, which are very expensive and complex.
Proceeding from this circumstance, embodiments of the present invention is based on a method and a device of the aforementioned type to be designed in such a way, so that this could be performed in a simple implementation form and with high speed.